This study examines the family behaviors- ethnic intermarriage and living arrangements of parents of their grown children - of people in Chicago between 1900 and 1920. It uses two sorts of data. The first is the series of IPUMS public use samples of the census, 1900-1910-1920, analyzed cross-sectionally. The second is a sample of 6500 men and women drawn from the 1920 IPUMS and linked back to their records in the 1910 and 1900 census, using standard genealogical methods. These data will be analyzed as a three-wave panel. The principal questions to be addressed arise from the assimilation model of immigrant migrant adaptation. This model posits a process of increasing similarity to the family patterns characterizing the host society. Evidence of such a process would be found in differences between older and newer immigrant groups, differences among individuals by years or generations in the U.S. (or, for blacks, in the North), and effects of other key indicators of assimilation such as occupational and residential location, naturalization, and speaking English the study distinguishes racial and ethnic groups (based on race, state or country of birth, and mother tongue) according to generation (for blacks, the comparison is between 1st and 2nd and later generation Northerners; for whites, it is between 1st, 2nd, and later generation Americans). The principal innovation in cross-sectional models of intermarriage and living arrangements is the inclusion of information on residence in an ethnic neighborhood and work in an ethnic niche of the labor force, both of which are interpreted as indicators of the strength of ethnic ties (or, inversely, of acculturation). The use of panel data to study these same topics is unique for historical studies, and allows some inherent limitations of a cross-sectional analysis to be overcome.